Motorized dental handpiece and control therefor



NOV. 19, 1968 STEMLER ET AL 3,411,209

MOTORIZED DENTAL HANDPIECE AND CONTROL THERE-FOR Filed July 30, 1964 4 sheets-Sheet 1 ill-11h FIG. 5

\\\r\\\| I\\- \I k |2a |30 M32 M34 136 I47 ,NVENTOR'S F'G |4 JOSEPH STEMLER KENNETH e. SLOTKOWSKl JOHN E. SARGEAN f ATTORNEYS NOV. 19, 1968 ST ET AL MOTORIZED DENTAL HANDPIECE AND CONTROL THEREFOR Filed July 30, 1964 4 Sheets-Sheet 2 FIG. l2 160 VIIIIII IIIIIIIIIII FIG. 2

INVENTORS H STEM%,ER TH G. SLO KowsKl E. SARG A T QZZZJ 1.4% ATTORNEYS EP NE NOV. 19, 1968 J STEMLER ET AL 3,411,209

MOTORIZED DENTAL HANDPIECE AND CONTROL THEREFOR Filed July 30, 1964 4 Sheets-Sheet 238 244 FIG. I3

INVENTORS JOSEPH STEMLER BY K NNETH e. SLOTKOWSK! HN E s R WANT ,6 KTTVORNEY NOV. 19, 1968 STEMLER ET AL 3,411,209

MOTORIZED DENTAL HANDPIECE AND CONTROL THEREFOR Filed July 30, 1964 4 Sheets-Sheet 4 406 me 420 334 FIG. 24

238 244 FIG. '9 ll! FIG.2O

INVENTOR. S

JOSEPH STEMLER BY ljSNNETH G. SLOTKOWSKI HN E. SARG ANT 246 F Wm 6 440;

United States Patent 3,411,209 MOTORIZED DENTAL HANDPIECE AND CONTROL THEREFOR Joseph Stemler, St. Clair Shores, Kenneth G. Slotkowski,

Oak Park, and John E. Sargeant, Clawson, Mich., assignors, by mesne assignments, to Ritter Pfaudler Corporation, Rochester, N.Y., a corporation of New York Filed July 30, 1964, Ser. No. 386,350 18 Claims. (Cl. 32-23) ABSTRACT OF THE DISCLOSURE The invention consists of a conventional dental handpiece having an electric motor structure directly connected thereto forming a rigid unit. There is a quick disconnect coupling between handpiece and motor. A flexible electric cord leads from the DC. motor to a foot controller provided with a rectifier and means for varying the amount of current to thereby control the motor speed.

In the past dentists have generally been restricted to work in a relatively confined area due to the size and weight of the equipment which is essential to the practice of their profession or have been limited to rather crude portable dental units which have made dental Work both painful for the patient and tedious for the dentist.

Further prior dental units even in fixed installations have often been lacking in versatility and awkard in use. For example, present standard handpieces in use by dentists are supported on a relatively cumbersome arrangement of pulleys, shafts and pivot connections and are connected for actuation to a fixed position power installation which is variously controlled by numerous hand operated dials, buttons and the like.

Also, the present dental units are often restricted to a single type of energy having limited and/or non-variable power range. The dentist is therefore required to purchase a plurality of separate units to effectively practice his profession with the most up'todate equipment for a particular job to be accomplished. Thus, both high speed and low speed dental units are advantageous at different times as are electric and air driven dental units any of which may require cooling air or water.

It is therefore an object of the present invention to provide a completely portable dental unit.

Another object is to provide an improved dental handpiece assembly.

Another object is to provide a dental unit including a hand-piece assembly having a drive motor included therein for movement therewith, a foot controller for providing variable power to the handpiece assembly and a flexible power cord connecting the foot controller and handpiece assembly.

Another object is to provide a dental unit as set forth above wherein the handpiece assembly includes a separate handpiece and drivc motor and means are provided for quickly connecting and disconnecting the handpiece from the drive motor.

Another object is to provide a dental unit as set forth above wherein the drive motor includes a drive shaft and further including an insulating connection between the motor drive shaft and dental handpiece.

Another object is to provide a dental unit as set forth above wherein the drive motor is provided with heat transfer means to heat the air and water passed to the handpiece assembly and cool the drive motor.

Another object is to provide a dental unit as set forth above wherein the drive motor is sealed against contamination.

Another object is to provide a dental unit as set forth "ice above wherein the foot controller includes foot actuated means for gradually varying the speed of rotation of the drive motor.

Another object is to provide a dental unit as set forth above wherein the foot controller includes rectifier means and electronic circuit means for maintaining a substantially constant but selectable voltage output over wide drive motor loads.

Another object is to provide a dental unit as set forth above wherein means are provided in the foot controller to indicate predetermined approximate drive motor speeds.

Another object is to provide a dental unit as set forth above wherein the foot controller further includes visible, foot actuated means for reversing 'the direction of rotation of the drive motor.

Another object is to provide a dental unit as set forth above wherein the foot controller further includes a separate circuit for supplying electric energy to operate accessory dental equipment.

Another object is to provide a dental unit as set forth above wherein the foot controller further includes separate foot actuated means for passing variable amounts of air and water to the dental handpiece assembly.

Another object is to provide a dental units as set forth above wherein the foot controller further includes separate means for supplying a variable supply of air for operation of an air turbine actuated dental handpiece.

Another object is to provide a dental unit as set forth above wherein the power cord connecting the foot controller with the handpiece assembly comprises an electric cable and separate conduits for passing water and air from the foot controller to the handpiece connected to the cable.

Another object is to provide a dental unit as set forth above and further including an adapter for use between the drive motor and handpiece of the handpiece assembly to permit the use of a plurality of handpieces with a single drive motor.

Another object is to provide a dental unit as set forth above including a portable telescopic equipment stand supported by the foot controller.

Another object is to provide a dental units as set forth above wherein dental tool rotational speeds of several hundred thousand revolutions per minute are possible.

Another object is to provide a dental unit as set forth above which is simple in construction, economical to manufacture and eflicient in use.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

FIGURE 1 is a perspective view of a dental unit constructed in accordance with the invention.

FIGURE 2 is a transverse cross section of the motor of the dental handpiece assembly illustrated in the dental unit of FIGURE 1 taken substantially on the line 22 in FIGURE 1.

FIGURE 3 is an enlarged elevation view of a portion of the dental unit illustrated in FIGURE 1 with the handpiece disconnected from the drive motor.

FIGURE 4 is an enlarged elevation view of the portion of the dental unit illustrated in FIGURE 3 with the drive motor and handpiece advanced toward each other and turned at right angles with respect to each other and the position thereof illustrated in FIGURE 3 as in disconnecting the drive motor and handpiece.

FIGURE 5 is an enlarged elevation view of a portion of the dental handpiece assembly, illustrated in FIGURE 1, partially broken away to show the insulating connection between the handpiece and drive motor thereof.

FIGURE 6 is a cross section of the dental handpiece assembly illustrated in FIGURE 1 taken substantially on the line 66 of FIGURE 5.

FIGURE 7 is an enlarged cross section view of the power cord connecting the foot controller to the handpiece assembly illustrated in FIGURE 1 taken substantially on the line 7-7 in FIGURE 1.

FIGURE 8 is a section view of a modification of the power cord illustrated in FIGURE 7.

FIGURE 9 is a rear elevation of the foot controller portion of the dental unit illustrated in FIGURE 1.

FIGURE 10 is a phantom view of the foot controller illustrated in FIGURE 1 illustrating the air and water valves and the air turbine valve positioned therein with respect to the actuating lever of the foot controller.

FIGURE ll is a partly broken away enlarged view of a portion of the foot controller illustrated in FIGURE 1.

FIGURE 12 is an enlarged section view of a portion of the foot controller of the dental unit illustrated in FIGURE 1 taken substantially on the line 12-12 in FIGURE 1.

FIGURE 13 is a schematic view of the electronic circuit of the foot controller illustrated in FIGURE 1.

FIGURE 14 is an enlarged longitudinal section view of an adapter for use in conjunction with a dental handpiece assembly constructed as illustrated in FIGURE 1, to permit the use of different handpieces with the same drive motor.

FIGURE 15 is an elevation view partly broken away of a telescopic stand for use in conjunction with the dental unit illustrated in FIGURE 1.

FIGURE 16 is a modification of the dental handpiece assembly illustrated in FIGURE 1 especially adapted for high speed operation.

FIGURE 17 is another modification of the dental handpiece assembly illustrated in FIGURE 1 again constructed to permit high speed operation.

FIGURE 18 is a diagrammatic plan view of modified rotational speed indicating structure for use in a foot controller as illustrated in FIGURE 1.

FIGURES 19-2l are schematic diagrams of modifications of a portion of the electronic circuit of the foot controller illustrated in FIGURE 1 as shown in FIGURE 13.

FIGURES 22-24 are schematic diagrams of different embodiments of the electronic circuit of the foot controller illustrated in FIGURE 1 for alternative substitution therein in place of the electronic circuit illustrated in FIGURE 13.

With particular reference to the figures of the drawings one embodiment of the present invention will now be considered in detail.

The portable dental unit 10 illustrated in FIGURE 1 includes the dental handpiece assembly 12, the foot controller 14 and the flexible power cord connection 16 extending therebetween.

The handpiece assembly 12 includes the electric drive motor structure 18 and the dental handpiece 20. A quick disconnect connection 22 is provided between the drive motor structure 18 and handpiece 20. The output shaft 88 of motor structure 18 is mechanically insulated from the rotatable shaft 54 of handpiece by coupling structure 24 positioned therebetween.

Foot controller 14 includes the foot lever 26 for starting and stopping and varying the speed of operation of the motor 82 of motor structure 18, push button switch structure 28 for reversing the direction of rotation of motor 82, the push button actuated solenoid operated valves 30 and 32 for passing air and water in selected quantities from the foot controller 14 to the handpiece assembly 12, a push button control switch 34 for an electric outlet on the foot controller 14 to permit operation of electric accessories with the dental unit 10 and a cam operated variable flow air valve 36, best shown in FIG- URE 10, for operation of an air turbine handpiece from the foot controller 14 with variable speed control.

Power cord 16, as illustrated in FIGURE 7, includes integral electric cable 38 and tubular conductors 40 and 42 for transferring electric energy, air and water from the foot controller 14 to the handpiece assembly 12.

The adapter 44 illustrated best in FIGURE 14 permits use of a plurality of standard dental handpieces with a single drive motor structure 18 in dental equipment 10. The telescopic dental equipment stand 46 is provided in conjunction with the dental unit 10 for use with the foot controller 14.

In operation the dental unit 10 is completely portable and may be operated at different speeds in opposite directions with air or water cooling of different dental handpieces and with different handpiece assemblies for different speed ranges. ln addition a plurality of separate accessories requiring electricity or air for motor power may be used with the dental unit 10 of FIGURE 1.

Different handpieces may be assembled with the drive motor structure 18 of the handpiece assembly 12 quickly and efliciently due to the quick disconnect connection 22 therebetween. Comfort of the patient and satisfaction of the dentist are promoted through the use of the mechanical insulating coupling structure 24 between the motor output shaft 88 and handpiece 20 which prevents transmission of mechanical vibration and noise between the motor structure 18 and the handpiece 20. The particular electronic circuit illustrated schematically in FIGURE 13 provides low voltage operation for the dental unit 10 at substantially constant speed at any speed selected in a selected direction and over a wide motor load range.

More specifically, the handpiece 20 of the handpiece assembly 12 includes a knurled tubular housing structure 50 to which a radially enlarged housing member 52 as shown in FIGURE 5 is threadedly secured and in which the rotatable drive shaft 54 is rotatably mounted. Drive shaft 54 is coupled through a convenient bevel gear mechanism for example to the spindle 56 in which the dental cutting device 58 is secured for rotation. Angled connecting housing 60 and spindle housing 62 are provided as required and clip means 64 are used to support the air and water conduits 40 and 42 of power cord 16 along the handpiece 20.

The radially enlarged member 52 is provided with the transverse opening therethrough which aids in the rapid disconnecting and changing of different handpieces 20 in the dental handpiece assembly 12. The dental handpiece 20 is a standard item of commerce and will not therefore be considered in further detail.

The motor structure 18 of the dental handpiece assembly. 12 includes the cylindrical elongated motor housing 72 which is integral with motor 82 and which is optionally finned to increase heat dissipation therefrom and which has a removable end 74 and an integrally constructed end 76 having opening 92 therethrough to which the flange 78 of the tubular member 80 is secured as shown in FIG- URE 5 by convenient means such as bolting or soldering.

The motor 82 integral with and mounted in housing 72 includes permanent magnets 84 and the rotatable armature 86, as shown diagrammatically in FIGURE 2. Thus in operation the permanent magnets 84 provide a magnetic brake to stop the rotation of the motor structure output shaft 88 substantially instantaneous on disconnection of the electric energy to the motor 82.

Motor 82 is a variable speed two pole direct current permanent magnet motor which is operable at voltages up to twenty-four volts and is sealed against contamination. Motor 82 is a commercially procurable item of commerce and may be purchased from the Kerr Manufacturing Company of Detroit, Mich., as Kerr motor, Model No. 6300. The motor 82 will therefore not be discussed in further detail.

In assembly, the electrical conductors 90 extend through end 74 of motor housing 72 to provide energy for the motor 82. End 74 is connected to the motor housing 72 by means of elongated hollow bolts 96 extending longitudinally of the motor housing 72 and through the motor 82 through or between the magnets 84, as shown in FIGURE 2.

The air and water conduits and 42 are connected to the hollow bolts by convenient means (not shown) whereby cooling is provided for the motor 82 in use due to the air and water passing through the hollow bolts 96 within the motor. The heat transfer from the motor to the material in the bolts 96 further preheats the air and water before it is dispensed at the point of use, thereby reducing the shock of the air and water to a patient.

The heat transfer and subsequent cooling of the motor 82 and heating of the air or water passed through the conductors 40 and 42 may be by means of an exterior jacket 98 if desired, as specifically shown in FIGURE 17.

The motor structure 18 may be rigidly connected to the handpiece 20. However, it is more desirable to provide a quick disconnect connection 22 between the motor structure 18 and handpiece 20 in most cases so that a single motor structure may be used with a plurality of different handpieces 20.

Thus in accordance with the invention the handpiece 20 is as previously indicated provided with a transverse opening in the end 68 extending transversely through the wall thereof. A leaf spring 100 is then secured by convenient means, such as rivets 102, in an elongated slot 104 in the tubular member 81) which is rigidly secured to the motor housing 72 by means of flange 78 as previously considered. The leaf spring 100 diverges from the tubular member at the end 106 thereof and includes at end 1116 the locking abutment 168 secured to the leaf spring by convenient means, such as riveting. The locking abutment 108 is provided with a cross section as shown best in FIGURE 5, and is provided with a surface 110 having a substantially forty-five degree slope thereto, also as shown best in FIGURE 5.

Thus in operation when it is desired to connect the handpiece 20 to the motor structure 18, the handpiece 21 is moved toward the motor structure 18 until the housing member 52 of the handpiece 20 is sleeved over the tubular member 86. The end 63 of the housing member 52 of the handpiece 20 will on advancing of the handpiece 20 toward the motor structure 18 ride on surface 110 of the locking abutment 108 and cam the abutment into the slot 104 so that the housing member 52 of the handpiece 20 covers the abutment 108. The housing member 52 is then rotated until the abutment 108 extends outwardly under bias of spring 101 into the transverse opening 70. At this time the handpiece 20 cannot be removed by either rotation of the handpiece 211 or movement of the handpiece away from the motor structure 18.

To disconnect the handpiece 20 from the motor structure 18 it is then necessary to advance the handpiece 20 toward the motor structure 18 to cam the locking abutment .108 out of the transverse opening 71), and to then rotate the handpiece 29 until the locking abutment 103 is out of axial alignment with the transverse opening 7 i), as shown in FIGURE 4. The handpiece 20 can then be removed by moving the handpiece 21 away from the motor housing structure 18.

In connecting and disconnecting the handpiece 21 from the motor structure 18 it will be understood that the air and water conduits 40 and 42 must be connected and disconnected in the usual manner.

The coupling 24- between the rotatable handpiece drive shaft 54 and the drive motor output shaft 88 is accomplished internally of the tubular member 80 as shown best in FIGURES. A connecting member 112 is fixedly secured to the shaft 88 by convenient means, such as pin 114. The connecting member 112 is provided with a tip 116 having a pair of angularly separated axially extending fingers 117 thereon, as illustrated best in FIGURE 6,

which tip connects with the engaging fingers .118 of the drive shaft 54 of handpiece 20.

When the motor 82 is energized the shaft 88 is caused to rotate the insulating member 112 which in turn rotates the shaft 54 of handpiece 20 to produce rotation of the spindle 56 in the usual manner. The motor shaft 83 is thus insulated from the drive shaft 54 of handpiece 20 by the member 112 so that transmission of noise and motor vibration to handpiece 20 is substantially eliminated.

The adapter 44 permits interchanging of a plurality of different standard dental handpieces, such as the standard dental contra-angles on a single motor structure 18. The adapter illustrated in FIGURE 14 includes an outer tubular housing 120 which is similar to the member 52 of the handpiece 20 in that it is provided with a transverse opening 122. A nose sleeve 126 which is tapered radially inwardly, axially outwardly of the tubular housing v1211 is positioned within the end 128 of tubular hous- 126 and secured therein by convenient means, such as silver solder. The end of the sleeve 126 is tapered radially inwardly to permit the end of a standard dental contraangle handpiece housing to fit thereover and be pressed thereon to provide a tight fit.

Bearing 130, bearing spacing sleeve 132 and bearing 134 are secured within the tubular housing 120 by the nut 136 threadedly connected to the housing member 120. The adapter shaft 138 is mounted in the bearings and 132 for rotation by means of the nut 140 in conjunction with the bearing spring retainer 142.

Bearing spring retainer 142 cooperates with bearing spring retainer 144 to secure the bearing preload spring 146 in posotion. The bearing preload spring 146 assures a tight fit without play for the bearing races and balls regardless of bearing wear so that noise in operation of the adapter 44 is reduced or eliminated.

Shaft .138 has the coupling member 147 having connecting fingers 148 secured thereto by convenient means, such as the set screw 150. The axial recess 152 in the end 154 of shaft 138 supports a friction chuck 156 on the interior thereof which may be tapered radially inwardly, axially inwardly of the recess 152 to firmly grip the rotatable drive shaft of a contra-angle or similar dental handpiece assembly to provide torque transfer between the adapter and drive shaft. The chuck 156 can also be threadedly retained in the shaft 138.

Thus it will be seen that a quick disconnect quiet operating adapter 44 is provided for use between a standard dental contra-augle handpiece 2i) and motor structure 18 as set forth above. A plurality of separate handpieces may be used with a single motor structure 18 and an adapter 44.

The power cord 16, as best shown in FIGURE 7, includes a main electric cable 38 including one or more electric conductors 90 extending therethrough to supply electrical power to the motor 82, as shown best in FIGURE 7. In accordance with the invention, a pair of separate conduits 419 and 42 for conducting air and water respectively to the dental handpiece assembly 12, as previously indicated, are produced integrally with the cable 38. The cable 38 and conduits 4t and 42 are of the same flexible, electric insulating material.

If desired the modified electric cable as shown in FIG- URE 8 may be a hollow tubular insulating member 156 having separate insulated conductors i158 extending therethrough. In this case the conduits 157 and 159 are produced integrally with the tubular insulating member 156. The conduits 4t and 42 may be separated from the cable 33 adjacent the connections to the motor 32 and the foot controller 14 to facilitate the connections therebetween as desired.

The foot controller 14, as shown best in FIGURE 1, includes a housing 160, a foot lever 26, motor direction reversing switching means 28 including push buttons 162 and 164, air valve 30 and water valve 32 and indicator lights therefor 166 and 168, the push button actuated electric accessory circuit including plug 188 and switch 34 and foot lever operated air valve 36 for operation of air turbine dental equipment connected to air inlet and outlet conduits 172 and 174 respectively. Air valve is connected to the air inlet and outlet conduits .176 and respectively while water valve 32 is connected to the water inlet and outlet conduits 180 and 42 respectively. The electrical inlet cable 184 from a convenient source of alternating current in the present disclosure is connected through foot controller 14 to the electric cable 38 and the electric accessory outlet 188.

In operation the switching means 28 determines the direction of rotation of motor 82 depending on which of the two push buttons 162 and 164 is depressed Push buttons 162 and 164 are better illustrated in FIGURE 12 in conjunction with the switch 190 which is rigidly mounted within the housing 160. The push buttons 162 and 164 are mounted for convenience in the bushings 2114 and 286 on a bracket 208 within the housing 160. Push buttons 162 and 164 operate switch 190 through the rigid lever 192 provided with the ends 194 and 196 extending at an angle to each other and including lost motion connections 198 and 200 to push buttons 162 and 164.

Thus pivoting of either end 194 or 196 of the lever 192 into a horizontal position will actuate the switch 190 to reverse the connections to the grounded plug 202, as best shown in the schematic diagram of the foot controller illustrated in FIGURE 13. The position of the push buttons I62 and 164 provides a visual indication of the direction of rotation of motor 82 energized from plug 202.

The solenoid actuated air and water valves 30 and 32, as shown best in FIGURE 10, provide a direct connection between the input and output air and water conduits 176 and 40, and 186 and 42 when they are energized. The valves 30 and 32 are provided with rotatable knobs 210 and 212 which may be prepositioned to provide a predetermined fiow of air or water through the valves on energization of the electric solenoids 270 and 266 contained therein. Solenoid operated valves are commercially available and will not therefore be considered in greater detail.

Switch 34 is a standard foot operated push button electrical switch. A circuit between the electric input cable 184 and the accessory output plug 188 of the foot controller 14 is completed on alternate depressions of the switch 34 with the foot pedal switch 242 closed. The energization of the circuit through accessory plug 188 is thus controlled by the initial movement of foot pedal 26 with switch 34 closed.

In addition to the valves 30 and 32 and the switch 34, the air valve 36 is provided to variably control the flow of air between the air conduits 172 and 174 for operation of an air actuated dential handpiece. Thus the foot lever 26 is pivotally mounted centrally on pivot mounting 214 and engages the valve actuating cam 216 on movement about pivot mounting 214 to more fully open or close the air valve 36.

The foot lever 26 is operable on movement to the right, as illustrated in FIGURES 1 and 10, to produce progressively greater speed of rotation of the motor 82, as will be more fully considered in conjunction with the electrical schematic of the foot controller 14 illustrated in FIGURE 13. Structure is provided in conjunction with the foot lever 26, as shown best in FIGURE 11, for providing indications of predetermined speeds of rotation. Thus foot lever 26 is provided with an opening 220 therethrough having the plug 222 inserted in one end thereof and the cam finger 224 spring urged by spring 226 from the other end thereof into the plurality of recesses 228 provided in the bottom of the slot 231' along which the foot lever 26 moves. The recesses 228 may be positioned to provide a difference in rotation of the spindle 56 therebetween of for example five thousand revolutions per minute.

Over-all operation of the foot controller will be considered in conjunction wi.h the schematic diagram illustrated in FlGURE 13.

The grounded plug 232 is connected to a source of electric energy of for example the usual one hundred fifteen volts alternating current to provide one hundred fifteen volts across the primary winding 234 of step-down transformer 236 through fuse 240 and approximately twenty-four volts root mean square across the secondary winding 238 of transformer 236. The circuit to transformer 236 is open until switch 242 is closed. Switch 242 is closed immediately on the starting of the movement of the foot lever 26 to the right from its spring biased leftwardmost position.

The voltage across the secondary winding of transformer 236 is rectified through the full wave rectifier bridge 244 to provide approximately thirty volts across the filter capacitor 246. The voltage divider including the fixed resistor 248 and the resistance element 250 of potentiometer 262 is connected across the output of the rectifier 244 in series With the voltage across the resistance element 250 being held to a predetermined voltage over a wide load range by the Zener diode 252 connected in parallel therewith.

Transistor 254 includes in its circuit a portion of the resistor 250. Thus the current through the collectoremitter circuit of transistor 254 is determined by the position of the wiper arm 261) to the potentiometer 262. Capacitor 264 is a filter for the bias circuit of transistor 254 which also acts as an electronic filter.

Thus, in over-all operation, as the foot lever 26 is moved to the right, the potentiometer wiper arm 269 moves up to produce more bias on the transistor 254 and increase the collector-emitter current of the transistor 254 to produce the same bias between the base-collector of the transistor 258, thus increasing the collector-emitter current therethrough. The direct current electric signal available at the plug 202 for the operation of motor 82 will thus be increased to increase the speed of motor 82.

The speed of the electric motor 82 is reduced on movement of the foot lever 26 to the left in an opposite manner since the potentiometer wiper arm 260 is moved down in FIGURE 13 to provide less bias on the transistor 254 to permit less current flow therethrough and thus restrict the current flow through the transistor 258 and motor 82 from plug 202 due to decreased bias on transistor 258.

As previously indicated the push button actuated reversing switch merely changes the connection to the plug 202 and the direction of current flow through the motor 82.

The electrical accessory output plug 188 is as shown connected through switch 34 directly across the terminals of the input plug 232 after switch 242.

Solenoids 266 and 270 of valves 30 and 32 are connected in parallel with the plug 188 so that as the motor 82 is energized when switch 242 is closed the valves 30 and 32 will be actuated to provide air and water to handpiece 20. Solenoid 266 together with the push button switch 268 and indicator light 168 are provided in conjunction with the valve 30, while the solenoid 270, push button switch 272 and indicator light 274 are provided in conjunction with the valve 32 to permit separate or simultaneous operation of the valves 30 and 32 and a visual indication thereof.

As illustrated in FIG. 19 the transformer 236 of the electronic circuit illustrated in FIGURE 13 may have variable resistance 320 in series with the primary windirng thereof and wiper arm 322 in parallel with a portion of the resistor 320 to vary the magnitude of the electric signal from plug 232 over conductor 184 fed to the primary winding 234 of transformer 236. Alternatively the transformer 236 may be a variable autotran former including the extra primary winding 324 and variable wiper arm 326, as shown in FIGURE 20, or the transformer 236 may be a tapped-transformer, as shown in FIGURE 9 21, having the signal magnitude selector switch 328 in circuit with the primary winding 234 of transformer 236.

Further the electronic circuits 330, 332 and 334 illustrated in FIGURES 22 through 24 may be substituted for the electronic circuit illustrated in FIGURE 13 in the foot controller '14. As shown in FIGURES 22 through 24 the electronic circuits 330, 332 and 334 do not include the accessory plug 188 and switch 34 or the solenoids 266 and 270 of the valves 30 and 32 or the switches 268 and 272 and lights 166 and 168 associated therewith. These elements can of course be added to the circuits of FIG- URES 22 through 24 as desired. Further the motor reversinrg switch 190 and plug 202 illustrated in FIGURE 13 have been shown only as a load coil in the circuit diagrams of FIGURES 22 through 24 for simplicity.

With particular respect to the electronic circuit 330 illustrated in FIGURE 22, electric energy is supplied to the primary Winding 344 of transformer 336 from plug 338 through fuse 340 on closing of the switch 342 by means of the foot pedal 26 of foot controller 14. The secondary winding 346 of transformer 336 is connected to the full wave bridge rectifier 348. To this point the circuit 330 of FIGURE 21 is entirely similar to the electronic circuit of FIGURE 13.

The full wave bridge rectifier348 supplies an electric signal to the load 350 indicated diagrammatically by the Secondary 346. The electric signal applied to the load 350 is maintained substantially constant by the capacitor 354 which is charged on conduction of the silicon controlled rectifier 252. The silicon controlled rectifier is protected in operation by the diode 356 against negative peak voltages and is protected against excessive currents by the resistor 358.

In operation the silicon controlled rectifier 352 conducts when the voltage on gate 359 is above a predetermined value as determined by the value of resistor 360 and conduction of the uni-junction transistor 362. The uni-junction transistor conducts from zero to 17.5 milliseconds depending on the setting of the wiper arm 364 of variable resistor 366 in series with the resistor 368 and the capacitor 370. Wiper arm 364 is mechanically connected to switch 342 and is movable with foot pedal 26.

In addition the silicon controlled rectifier is being switched at one hundred twenty cycles per second in accordance with the output of the electric signal from full wave rectifier 348. The resulting output to load 350 is thus substantially constant and variable in amplitude in accordance with the setting of the wiper arm 346 of variable resistance 366 in accordance with the position of the foot pedal 26.

The electronic circuit 332 of FIGURE 23 is similar to circuit 330 in that an electric signal is applied through plug 372 over the primary winding 374 of transformer 376 to the secondary winding 378 of the transformer. The signal fed to the primary winding 374 of transformer 376 is however modulated in accordance with the conductance of the silicon controlled rectifier 380 under control of the uni-junction transistor 382.

Again the on-time of the uni-junction transistor 382 may be varied from Zero to 17.5 milliseconds by movement of the wiper arm 384 of variable resistor 386 and closing of switch 388 both under the control of the foot pedal 26. The output of the silicon controlled rectifier 380 is also modulated by the uni-junction transistor at one hundred twenty cycles per second to the output from the full wave bridge rectifier 390.

Thus in a sequence of operation the electric signal from full wave bridge rectifier 390 is fed in series across the resistors 392 and 394 and the variable resistance 386 to charge the capacitor 396. When the capacitor 396 reaches a predetermined voltage level the uni-junction transister 382 will conduct discharging the capacitor 396 through the resistance 398 to produce a voltage to trigger the silicon controlled rectifier 380. At a predeter- 10 mined time later, dependent upon the setting of the wiper arm 384, the uni-junction transistor 382 will be rendered non-conducting and the silicon controlled rectifier will be cut off so that the output signal on the primary winding 374 of transformer 37 6 varies in accordance with the setting of the wiper arm 384.

The signal from the secondary winding 378 of transtformer 37 6 is then fed through full wave rectifier 400 and filter capacitor 402 to load 404.

The electronic circuit 334 is somewhat difierent from the circuits 330 and 332 in that the signal from the plug 406 is fed across the variable resistance 408 and the resistance 410 through the foot pedal operated switch 412 and fuse 414 to charge the capacitor 416 until the voltage across the capacitor 416 reaches the break-over point of the diode alternating current switch 418, at which time the capacitor 416 discharges through the diode alternating current switch 418 to cause the tri-conductor alternating current switch 420 to conduct through the primary winding 422 of transformer 424. Again the signal through the primary winding 422 of transformer 424 is of a magnitude determined by the position of the wiper arm 426 which is again controlled by the foot pedal 26 along with the off-switch 412.

The signal from the secondary winding 428 of the transformer 424 is then lfed through the full wave rectifier 430, filtered through capacitor 432 and applied to the load 434.

If desired dental equipment stand 46, as shown in FIGURE 15, may be secured to the loot controller 14 by means of a mounting bar 276 and bolt 278 operating in conjunction with the arcuate foot 280 on, and opening 282 through the telescoping shaft 284 having equipment tray 286 secured to the top thereof. A bracket 288 may be provided on the tray 286 in which the dental handpiece assembly 12 may be secured while it is not in use.

The foot controller 14, dental handpiece assembly 12, connecting power cord 16, adapter 44 and necessary direct current power supplies in place of the alternating power supply, transformer and rectifier may be conveniently packaged in a portable case for use in remote locations. The telescoping equipment stand and a plurality of different interchangeable dental handpieces, dental drills, burrs and the like may also be included in the portable case.

While the invention including the foot controller 14, motor 82, and connecting power cord 16 have been disclosed in conjunction with a standard straight or angle dental handpiece for operation between zero and twentyfive thousand revolutions per minute, it will be understood that high speed operation is possible with the foot controller and motor structure under consideration. Thus as shown in FIGURES 16 and 17, the dental handpiece assemblies 290 and 292 may be operated at several hundred thousand revolutions per minute through appropriate ratios between the pulleys 294 and 296 and the pulleys 298 and 300. The high speed dental handpieces illustrated in FIGURES l6 and 17 illustrate the versatility of connection of the motor structures 302 and 304 with the handpieces 306 and 308 respectively through various arrangements of direction changing pulleys 310, 312 and 314 and drive belts 316 and 318.

While one embodiment of the present invention and modifications thereof have been disclosed in detail, it will be understood that other embodiments and modifications are contemplated. Thus, for example, the structure illustrated in FIGURE 18 may be substituted for the structure illustrated in FIGURE 11 to provide an indication of the speed of rotation to motor 82. The structure illustrated in FIGURE 18 comprises a lever 440 pivotally mounted in the foot controller 14 by pivot mounting means 442 and extending horizontally just above the foot pedal 26. Lever 440 includes the notches 444 in the face 446 thereof and is urged in a counterclockwise direction, as illustrated in FIGURE 18, by the spring 448. Pin 450 is provided on foot pedal 26 extending upwardly therefrom and engages the notches 444 as the foot pedal 26 is moved counterclockwise about the pivot mounting 214 thereof to provide the previously ientioned indications of the speed of rotation of the motor 82. It is therefore the intention to include all embodiments and modifications of the invention as are disclosed by the appended claims within the scope of the invention.

What we claim as our invention is:

1. Portabie dental apparatus comprising a dental handpiece assembly including a dental handpiece and a motor structure forming a rigid unit supportable by hand which motor structure includes an electric drive motor for the dental handpiece, said motor being a permanent magnet fixed field direct current motor providing magnetic braking for the dental handpiece, a quick disconnect coupling between said dental handpiece and said motor structure, a foot controller, a flexible power cord extending between the handpiece assembly and foot controller for supplying direct current to said motor, and means for connecting said foot controller to a source of electric current.

2. Structures as set forth in claim 1 wherein the dental handpiece includes a cylindrical housing member and the motor structure includes a tubular member having a slot therein receivable within the cylindrical housing member and the quick disconnect connection comprises a transverse opening through the housing member of the handpiece adjacent one end thereof, a spring secured to the tubular member within the slot therein and at one end thereof and a locking abutment secured to the spring urged outwardly of the tubular member by the spring and adapted to fit within the transverse opening through the housing member of the handpiece and having sides extending substantially perpendicularly to the axis of the tubular member with the exception of the axially inner side thereof which is inclined at an angle to the axis of the tubular member radially inwardly axially thereof to permit camming of the locking abutment out of the opening on movement of the dental handpiece toward the motor structure.

3. Structures as set forth in claim 2 wherein the dental handpiece includes a rotatable drive shaft and the electric motor includes an output shaft and further including a vibration and noise insulating connection between the motor output shaft and the dental handpiece drive shaft.

4. Structure as set forth in claim 3 wherein the insulating connection between the motor output shaft and the dental handpiece drive shaft comprises an insulating member of resilient material secured to the motor shalt for rotation therewith and including a nosepiece having angularly spaced axially extending connecting fingers formed thereon and complementary connecting fingers extending from the rotatable shaft of the dental handpiece into engagement with the connecting fingers on the insulating member.

5. Structure as set forth in claim 4 wherein the motor structure further includes a housing having one open end with the motor positioned within the housing, a cover for the open end of the housing and hollow bolts extending axially completely through the housing connecting the cover to the housing for passing cooling air and water through the motor.

6. Structure as set forth in claim 5 wherein the motor structure includes a motor housing and a separate heat exchange jacket positioned around the motor on the exterior of the housing through which air and water for use in the dental handpiece are passed to cool the motor and heat the air and water.

7. Structure as set forth in claim 1 wherein the foot controller comprises a housing, a pivot mounting within the housing, a foot lever mounted on the pivot mounting for horizontal pivotal movement, switch means operably associated with one end of the lever and an electronic circuit including said switch means for providing a variable magnitude electric signal to said motor from said foot controller on pivotal movement of said lever.

8. Structure as set forth in claim 7 wherein the electronic circuit includes means for providing a substantially constant electric signal for predetermined positions of said lever with variable load applied to said motor.

9. Structure as set forth in claim 7 and further including means for reversing the polarity of the electric signal fed to said motor.

10. Structure as set forth in claim 9 wherein the means for reversing the polarity of the electrical energy fed to said motor comprises a pair of foot operated push buttons, an electric switch, an angled lever centrally pivoted to said switch and a lost motion connection between each of the push buttons and the pivoted lever.

11. Structure as set forth in claim 7 wherein the foot controller includes separate push button operated, solenoid actuated valves for passing air and water to the dental handpiece from the foot controller.

12. Structure as set forth in claim 11 wherein the separate push button operated solenoid actuated valves include means for varying the quantity of air and water fed to the dental handpiece on energization thereof.

13. Structure as set forth in claim 7 wherein the foot controller includes a variable volume cam actuated valve for passing air to an air turbine handpiece operably associated with the foot lever for varying the air fed to an air turbine handpiece in accordane with the pivoted position of the foot lever.

14. Structure as set forth in claim 7 wherein the foot controller further includes an electric outlet and a push button switch for selectively supplying electric energy to the outlet to permit operation of auxiliary electric equipment connected to the outlet on actuation of the push button switch.

15. Structure as set forth in claim 7 and further including means for indicating predetermined intermediate positions in the pivotal movement of the foot controller to provide approximate handpiece rotational speed indications.

16. Structure as set forth in claim 15 wherein the means for providing position indications of the foot lever comprises a slot in the housing through which the lever projects, a plurality of spaced apart arcuate recesses in one surface of the slot and a spring urged cam finger carried by the foot lever and operable to cam into the arcuate recesses on pivotal movement of the lever along the slot.

17. Structure as set forth in claim 15 wherein the means for providing position indications of the foot lever comprises a second lever having a plurality of notches in one side thereof pivotally mounted at one end and extending transversely of the foot lever, a pin secured in the foot lever adjacent the notches in the second lever for camming into and out of the notches on pivotal movement of the foot lever and resilient means urging the notched lever in a direction to bias the pin into the notches.

18. Structure as set forth in claim 2 and further including an adapter positioned between the dental handpiece and the motor structure to permit the quick interchange of a plurality of diflerent dental handpieces with a single motor structure.

References Cited UNITED STATES PATENTS 2,876,015 3/1959 Steuer et a1 32-26 3,101,542 8/1963 Fodor 32-27 3,209,457 10/1965 Billin et al. 32-22 3,210,847 10/1965 Prufer 32-27 3,213,537 10/1965 Balamuth et al 32-28 3,229,369 1/1966 Hoffineister et al 32-27 3,280,458 10/1966 Deeley et al. 32-22 2,396,007 3/1946 Happe et al. 32-26 LOUIS G. MANCENE, Pri'ma/y Examiner.

R. PESHOCK, Assistant Examiner. 

